1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material and, more particularly, to a silver halide photographic light-sensitive material having a low fog, high sensitivity, and improved response to pressure.
2. Description of the Related Art
Recently, requirements for photographic silver halide emulsions have become strict, and higher level demands have arisen for toughness, such as response to pressure, in addition to photographic properties, such as a high sensitivity and a good graininess.
Methods of manufacturing and techniques of using tabular silver halide grains are disclosed in U.S. Pat. Nos. 4,434,226, 4,439,520, 4,414,310, 4,433,048, 4,414,306, and 4,459,353. Known advantages of grains of this type are improvements in sensitivity including an improvement in spectral sensitization efficiency obtained by sensitizing dyes, an improvement in the relationship between sensitivity and graininess, an improvement in sharpness derived from specific optical properties of tabular grains, and an improvement in covering power.
JP-A-63-220238 ("JP-A" means Published Unexamined Japanese Patent Application) and JP-A-1-201649 disclose tabular silver halide grains in which dislocation lines are introduced intentionally.
It is demonstrated that tabular grains in which dislocation lines are introduced are superior in photographic characteristics, such as sensitivity and reciprocity, to those having no dislocation lines, and that the use of these grains makes it possible to improve the sharpness and the graininess of a light-sensitive material.
To further increase the sensitivity of silver halide grains, it is considered preferable that dislocation lines be introduced to a limited position at a high density in each individual grain and uniformly between grains in terms of the homogeneity of each grain, the efficiency of chemical sensitization, and the concentration of latent image formation sites.
The present invention relates to a technique of controlling introduction of dislocation lines to particularly the fringe portion of a silver halide tabular grain.
JP-A-3-189642 discloses that a silver halide emulsion with a high sensitivity and improved graininess, gradation, and fog can be obtained by using tabular silver halide grains having 10 or more dislocation lines per grain at grain fringe portions.
In the conventional dislocation introducing technique, however, such as disclosed in the above patent application, increasing the density of dislocations is inconsistent with limiting their positions.
That is, introducing dislocation lines at a higher density to the fringe portion of a tabular grain causes unintended dislocation lines at the major faces of the grain, making it impossible to introduce dislocations uniformly between individual grains.
The present inventors have tried to eliminate grains other than those having dislocation lines essentially in only their fringe portions, i.e., grains having a large number of dislocation lines in their major faces, for there is the possibility that mixing of these grains into an emulsion leads to degradation of the photographic performance (e.g., an increase in fog, a decrease in sensitivity, and a degradation in response to pressure) of the emulsion.
The present invention aims at introducing dislocation lines essentially to only a grain fringe portion in each grain, while maintaining a high density of dislocation lines, and uniformly between individual grains, thereby forming grains that cannot be reached by JP-A-3-189642.